ActiveRecord 中的随机记录 [英] Random record in ActiveRecord

问题描述

我需要通过 ActiveRecord 从表中获取随机记录.我遵循了 2006 年的 Jamis Buck.

I'm in need of getting a random record from a table via ActiveRecord. I've followed the example from Jamis Buck from 2006.

但是，我还通过 Google 搜索找到了另一种方式(由于新用户限制，无法使用链接进行归因):

However, I've also come across another way via a Google search (can't attribute with a link due to new user restrictions):

 rand_id = rand(Model.count)
 rand_record = Model.first(:conditions => ["id >= ?", rand_id])

我很好奇这里的其他人是如何做到的，或者是否有人知道哪种方法更有效.

I'm curious how others on here have done it or if anyone knows what way would be more efficient.

推荐答案

如果没有至少两个查询，我还没有找到一种理想的方法.

I haven't found an ideal way to do this without at least two queries.

以下使用随机生成的数字(最多为当前记录数)作为偏移量.

The following uses a randomly generated number (up to the current record count) as an offset.

offset = rand(Model.count)

# Rails 4
rand_record = Model.offset(offset).first

# Rails 3
rand_record = Model.first(:offset => offset)

老实说，我一直在使用 ORDER BY RAND() 或 RANDOM()(取决于数据库).如果您没有性能问题，那就不是性能问题.

To be honest, I've just been using ORDER BY RAND() or RANDOM() (depending on the database). It's not a performance issue if you don't have a performance issue.

这篇关于ActiveRecord 中的随机记录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！